Life expectancy estimates that were made by WHO Headquarters for the World Health Report. Special techniques were used to produce life tables when routine vital statistics were not available or were incomplete. For some countries, where deaths registration is known to be incomplete, these estimates may differ significantly from the directly calculated life expectancy based on the official mortality and population data as reported to the WHO.

Demographic techniques [(i) the Bennet-Horiuchi method, (ii) the Simple Growth Balance method and (iii) the Generalized Growth Balance method] were first applied to assess the level of completeness of the recorded data for adults. Death rates were adjusted accordingly. The Brass Logit System of Model Life Tables was then used to generate trends in the parameter estimates (alpha and beta), separately for males and females, using the latest available country life table as a standard. Time series techniques were then used to forecast the alpha and beta parameter estimates corresponding to the year 2000, from which the above life tables, by sex, were obtained. All available survey, census and vital registration data were assessed, adjusted and averaged to estimate the trend in child mortality during the 1980's and the 1990's. This trend was then projected to obtain estimates of child mortality for the year 2000.